Toyota is universally assumed to have lost money on every first-generation Prius hybrid it built from 1997 to 2003, and only started to turn a profit somewhere during that car's second generation from 2004 to 2009.

Lower-than-planned sales of the Nissan Leaf over its seven-year life are widely assumed to have lost money for its maker.

And while Tesla Motors claims to turn a profit on its Model S and Model X luxury electric cars, those vehicles have not generated anywhere near the cash to invest in future products and expand its production.

Tesla has lost money continuously for more than 12 years, save for two marginally profitable quarters, sustained by injections of more than $2 billion in venture funding and stock sales.

“Our internal focus is to make GM the first maker of profitable, highly desirable, range-leading, and obtainable electric transportation,” CEO Barra said last month in the company's first-quarter earnings call for investors, analysts, and media.

Reuss called the goal the "mantra" of product development, though he wouldn't project when that could be achieved.

More than 20 years of data indicates that small "consumer format" lithium-ion cells have fallen at an average of 7 percent a year. Since 2010, the declines in larger cells used in vehicles have exceeded that rate.

Previously, GM had said it hoped to hit a cost of $100 per kilowatt-hour by 2022. More recently, Reuss expressed confidence that "we'll be there before then, I know we will."

Whether those cars will be priced comparably to similar vehicles with combustion engines, however, wasn't clear.